1. Field of the Invention
The invention relates to displays and portable computers, and more particularly to a portable computer system incorporating a rear projected display apparatus to increase the effective viewing area of the display without negatively impacting the form factor of the portable computer.
2. Description of the Related Art
Portable computers have become an everyday fixture in many people""s personal and professional lives. Due to their mobility and versatility, portable computers are even beginning to displace desktop computers in many offices. Despite the fact that the average display size in portable computers has increased over the years, however, screen sizes remain too small for many applications requiring a large viewing area. More specifically, today""s portable computers often include displays ranging from 10.4-inches to 12.1-inches. Many computer users accustomed to working with large desktop CRT monitors perceive these smaller portable computer displays as being inadequate.
Somewhat larger screens for portable computers have been developed. However, displays cannot be made arbitrarily large. The effective size limit for today""s display technologies is restricted by numerous practical and technical limitations. For example, the weight added to a portable computer by increasing its display size may be undesirable, and is often a major consideration. The form factor specifications of a portable computer, and particularly the width and length dimensions of the base portion, may also impose size limitations on the display. Further, problems in the manufacturing process, including problems with defects and poor yields, make larger displays much more expensive to produce. These manufacturing problems are inherent and arise from basic design of traditional displays, such as the active-matrix (AM) or thin-film-transistor (TFT) liquid crystal displays (LCDs).
Such displays may incorporate hundreds of thousands of transparent transistors driving a grid of electrical traces to control operation of liquid crystal fluid structure to generate images. As the size and resolution of a display increases, more transistors are required. More transistors increases the likelihood of defects, which often render the display useless. Similar manufacturing problems plague other imaging technologies, such as polymer dispersed liquid crystal displays (PDLCDs) and field emission displays (FEDs). As a result, display manufacturers often focus on improving image quality and reducing the power-consumption and weight of portable displays, rather than increasing display area.
A portable computer system according to the present invention consists of a base portion and a rear projection display. The rear projection display is housed in a display enclosure that is movable between an open position and a closed position, and incorporates a deformable projection surface. When the display enclosure is opened, the projection surface is configured to expand beyond the form factor dimensions of the base portion of the portable computer. Preferably, the projection surface is a pliable material that can be safely deformed or collapsed within the projection display enclosure when closed.
In addition to the projection surface, the rear projection display is comprised of an image generator/source or display panel and an optical system for projecting an image from the image generator onto the projection surface. When the projection display enclosure is in an open position, its components are separated by a distance sufficient to allow proper orientation and operation of the optical system. A rear projected display according to the invention thereby permits viewing angles and clarity comparable to that of many traditional display technologies. In one embodiment of the invention, expansion of the projection surface is optional, affording a smaller viewing area when the portable computer is operated in tight spaces. In another embodiment of the invention, the projection surface is approximately the size of a traditional portable computer display, but the image generator or display panel is smaller, lighter and less costly.
Thus, a rear projection display according to the present invention allows the effective viewing area of a portable computer display to be increased without negatively impacting the form factor dimensions, cost or weight of the portable computer.